summaryrefslogtreecommitdiff
path: root/jni/ruby/lib/rinda/rinda.rb
blob: d9cd3782a0f9250bafad96ba23b325438285104d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
require 'drb/drb'
require 'thread'

##
# A module to implement the Linda distributed computing paradigm in Ruby.
#
# Rinda is part of DRb (dRuby).
#
# == Example(s)
#
# See the sample/drb/ directory in the Ruby distribution, from 1.8.2 onwards.
#
#--
# TODO
# == Introduction to Linda/rinda?
#
# == Why is this library separate from DRb?

module Rinda

  ##
  # Rinda error base class

  class RindaError < RuntimeError; end

  ##
  # Raised when a hash-based tuple has an invalid key.

  class InvalidHashTupleKey < RindaError; end

  ##
  # Raised when trying to use a canceled tuple.

  class RequestCanceledError < ThreadError; end

  ##
  # Raised when trying to use an expired tuple.

  class RequestExpiredError < ThreadError; end

  ##
  # A tuple is the elementary object in Rinda programming.
  # Tuples may be matched against templates if the tuple and
  # the template are the same size.

  class Tuple

    ##
    # Creates a new Tuple from +ary_or_hash+ which must be an Array or Hash.

    def initialize(ary_or_hash)
      if hash?(ary_or_hash)
        init_with_hash(ary_or_hash)
      else
        init_with_ary(ary_or_hash)
      end
    end

    ##
    # The number of elements in the tuple.

    def size
      @tuple.size
    end

    ##
    # Accessor method for elements of the tuple.

    def [](k)
      @tuple[k]
    end

    ##
    # Fetches item +k+ from the tuple.

    def fetch(k)
      @tuple.fetch(k)
    end

    ##
    # Iterate through the tuple, yielding the index or key, and the
    # value, thus ensuring arrays are iterated similarly to hashes.

    def each # FIXME
      if Hash === @tuple
        @tuple.each { |k, v| yield(k, v) }
      else
        @tuple.each_with_index { |v, k| yield(k, v) }
      end
    end

    ##
    # Return the tuple itself
    def value
      @tuple
    end

    private

    def hash?(ary_or_hash)
      ary_or_hash.respond_to?(:keys)
    end

    ##
    # Munges +ary+ into a valid Tuple.

    def init_with_ary(ary)
      @tuple = Array.new(ary.size)
      @tuple.size.times do |i|
        @tuple[i] = ary[i]
      end
    end

    ##
    # Ensures +hash+ is a valid Tuple.

    def init_with_hash(hash)
      @tuple = Hash.new
      hash.each do |k, v|
        raise InvalidHashTupleKey unless String === k
        @tuple[k] = v
      end
    end

  end

  ##
  # Templates are used to match tuples in Rinda.

  class Template < Tuple

    ##
    # Matches this template against +tuple+.  The +tuple+ must be the same
    # size as the template.  An element with a +nil+ value in a template acts
    # as a wildcard, matching any value in the corresponding position in the
    # tuple.  Elements of the template match the +tuple+ if the are #== or
    # #===.
    #
    #   Template.new([:foo, 5]).match   Tuple.new([:foo, 5]) # => true
    #   Template.new([:foo, nil]).match Tuple.new([:foo, 5]) # => true
    #   Template.new([String]).match    Tuple.new(['hello']) # => true
    #
    #   Template.new([:foo]).match      Tuple.new([:foo, 5]) # => false
    #   Template.new([:foo, 6]).match   Tuple.new([:foo, 5]) # => false
    #   Template.new([:foo, nil]).match Tuple.new([:foo])    # => false
    #   Template.new([:foo, 6]).match   Tuple.new([:foo])    # => false

    def match(tuple)
      return false unless tuple.respond_to?(:size)
      return false unless tuple.respond_to?(:fetch)
      return false unless self.size == tuple.size
      each do |k, v|
        begin
          it = tuple.fetch(k)
        rescue
          return false
        end
        next if v.nil?
        next if v == it
        next if v === it
        return false
      end
      return true
    end

    ##
    # Alias for #match.

    def ===(tuple)
      match(tuple)
    end

  end

  ##
  # <i>Documentation?</i>

  class DRbObjectTemplate

    ##
    # Creates a new DRbObjectTemplate that will match against +uri+ and +ref+.

    def initialize(uri=nil, ref=nil)
      @drb_uri = uri
      @drb_ref = ref
    end

    ##
    # This DRbObjectTemplate matches +ro+ if the remote object's drburi and
    # drbref are the same.  +nil+ is used as a wildcard.

    def ===(ro)
      return true if super(ro)
      unless @drb_uri.nil?
        return false unless (@drb_uri === ro.__drburi rescue false)
      end
      unless @drb_ref.nil?
        return false unless (@drb_ref === ro.__drbref rescue false)
      end
      true
    end

  end

  ##
  # TupleSpaceProxy allows a remote Tuplespace to appear as local.

  class TupleSpaceProxy
    ##
    # A Port ensures that a moved tuple arrives properly at its destination
    # and does not get lost.
    #
    # See https://bugs.ruby-lang.org/issues/8125

    class Port # :nodoc:
      attr_reader :value

      def self.deliver
        port = new

        begin
          yield(port)
        ensure
          port.close
        end

        port.value
      end

      def initialize
        @open = true
        @value = nil
      end

      ##
      # Don't let the DRb thread push to it when remote sends tuple

      def close
        @open = false
      end

      ##
      # Stores +value+ and ensure it does not get marshaled multiple times.

      def push value
        raise 'port closed' unless @open

        @value = value

        nil # avoid Marshal
      end
    end

    ##
    # Creates a new TupleSpaceProxy to wrap +ts+.

    def initialize(ts)
      @ts = ts
    end

    ##
    # Adds +tuple+ to the proxied TupleSpace.  See TupleSpace#write.

    def write(tuple, sec=nil)
      @ts.write(tuple, sec)
    end

    ##
    # Takes +tuple+ from the proxied TupleSpace.  See TupleSpace#take.

    def take(tuple, sec=nil, &block)
      Port.deliver do |port|
        @ts.move(DRbObject.new(port), tuple, sec, &block)
      end
    end

    ##
    # Reads +tuple+ from the proxied TupleSpace.  See TupleSpace#read.

    def read(tuple, sec=nil, &block)
      @ts.read(tuple, sec, &block)
    end

    ##
    # Reads all tuples matching +tuple+ from the proxied TupleSpace.  See
    # TupleSpace#read_all.

    def read_all(tuple)
      @ts.read_all(tuple)
    end

    ##
    # Registers for notifications of event +ev+ on the proxied TupleSpace.
    # See TupleSpace#notify

    def notify(ev, tuple, sec=nil)
      @ts.notify(ev, tuple, sec)
    end

  end

  ##
  # An SimpleRenewer allows a TupleSpace to check if a TupleEntry is still
  # alive.

  class SimpleRenewer

    include DRbUndumped

    ##
    # Creates a new SimpleRenewer that keeps an object alive for another +sec+
    # seconds.

    def initialize(sec=180)
      @sec = sec
    end

    ##
    # Called by the TupleSpace to check if the object is still alive.

    def renew
      @sec
    end
  end

end